The object of the present invention is a method for manufacturing a container, such as a primary packaging, of the type comprising two or more compartments.
The method according to the invention can be applied, for example, to the manufacture of a control indicator of conservation temperature for refrigerated products such as the one described in patent WO/9963313. The temperature control device described in that patent is in the form of an enclosure consisting of two compartments separated by a narrowing capable of opening or tearing upon stress. The freezing of the liquid products contained within the compartments causes these products to dilate, which results in the opening of the narrowing separating the two compartment. Consequently, when the ambient temperature reaches the melt temperature of the products, the latter recover their liquid state and can thus mix within the two compartments because of the absence of a tight separation between the two compartments.
By predetermined stress will be meant herein either the stress that is capable of breaking the separation between the compartments of the container, such as thermal stress described above, or mechanical stress that is applied voluntarily from the outside of the container, such as, for example, a manual pressure. The predetermined character of the stress not only involves the nature of this stress (either thermal, mechanical, etc.) but also the width of the stress (temperature range, amplitude of forces, etc.).
A medical bag is also known from EP 1 424 956, having at least two compartments, which is made up of a flexible polymer material and is intended to make medical mixtures. This bag is made by means of welding on the edge areas of a folded flexible sheet of polymer material while the two compartments are separated from each other by means of a welding which has been made at a lower temperature than the edge welding temperature. Thereby, this welding that has been made at a lower temperature is more fragile and hence tearable under the effect of a force ranging between 5N e 20 N. The thus-obtained flexible bag can contain two different products separated within each compartment and the breakage of the separation welding allows these two products to be admixed in order to use the thus-obtained mixture. However, while such flexible bag can be appropriately used in the medical field to contain drug solutions, it however has some drawbacks. In fact, this flexible bag may be fragile when handled, in the event of impacts or stress applied to the bag, which may result in an early breakage of the compartments leading to an undesired mixing of the products. Further, such a bag may not be of use as a control indicator of conservation temperature for refrigerated products, because the dilation of the contents upon freezing would be absorbed by the flexibility of the material making up the bag.
A method for manufacturing such type of a bag is also provided in EP 0 972 506 in which two sheets of plastic material in the form of a multi-layer film are superimposed and welded along the periphery thereof, a middle portion separating the bag in two compartments. This separating portion is obtained by the adhesion of the two superimposed sheets resulting from a method of electron-beam crosslinking of the multi-layer film. Also in this case, a pressure of a sufficient force applied to the bag allows breaking the adhesion and forming a passageway within the compartments, thus allowing the contents thereof to be admixed. Furthermore, as with the flexible bag described above, any stress that is undesirably applied thereto while it is being handled may lead to an early breakage of the separation. Accordingly, this bag cannot be used as a storage temperature control indicator for refrigerated products.
It is understood that, in order to protect the products against this type of consequences arising from impacts, for example, it is known to manufacture non-flexible containers which have some rigidity such as those obtained according to the manufacturing method described in EP 1 136 230, in which two sheets of heat-sealable material are welded in order to define a contents cell having an opening. This cell is then placed within a mould, a moulding fluid being then introduced through the opening of the cell within said cell such that the latter will match the inner shape of the mould while hiding the welding within the container. However, this method does not allow providing a container with a separation defining compartments.
The object of the present invention is thus to provide a method for manufacturing a container, such as a primary packaging, of the type comprising at least two compartments, which can function as those described in the patents WO 99/63313, EP 0 972 506 and EP 1 424 056 but does not suffer from the drawbacks thereof and is both easy to make and effective.